1. Technical Field
This invention is related to the field of internal combustion ignition systems. More particularly, it is related to an apparatus and method of optimizing the air to fuel ratio of a combustion mixture when the engine is operated at wide open throttle condition.
2. Discussion
The prior art includes a variety of conventional methods for detecting and using ionization current in a combustion chamber of an internal combustion engine. However, each of the various conventional systems suffers from a great variety of deficiencies. For example, prior art ionization current detection circuits are generally too slow and generate a current signal with low signal-to-noise ratio.
Normally, oxygen sensors are used when controlling an air to fuel ratio. The oxygen sensor measures the presence of oxygen in the air to fuel mixture. However, when operating an engine at wide open throttle, the air to fuel mixture is outside the stoichiometric range, normally below the stoich. Due to the non-stoich operation at wide open throttle, the oxygen sensor (which generates either a rich or a lean signal) cannot be used as an indicator of air to fuel ratio.